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Properties.—Crystallises in needles; m. p. 121°; on heating-
it melts and sublimes ; soluble in hot water, alcohol and ether.
It distils in steam.

Reactions.—i. Make a neutral solution of ammonium benzoate
by adding excess of ammonia to benzole acid and boiling until
neutral To different portions add solutions of calcium chloride,
ferric chloride, silver nitrate and lead acetate and note the
results. .

2. Grind up o'5 gram of the acid with four times the weight of
soda-lime and heat gently at first and then more strongly.
Vapours of benzene will be given off, which may be detected by
the smell. CGH5CO.OH + CaO = CGH6 + CaCO3,

See Appendix, p. 302,

m-Nitro, m-Amino- and m-Hydroxybenzoic Acid,

/NO,      r „ /NH,      r H /OH         i


40 grms. benzoic acid. *
..'•"' '                           80     „     potassium nitrate.
TOO   c.c.   cone, sulphuric acid.
The benzoic acid and potassium nitrate are mixed and care-
fully powdered. The sulphuric acid is warmed to 70° and
stirred mechanically, whilst the mixture of benzoic acid and
nitrate is added slowly, so that the temperature does not exceed
80°. When all is added the temperature is raised to 90°, and
kept at this temperature until the nitrated acid separates as an
oily layer on the surface. On cooling, the layer solidifies and
can be separated. It is then distilled in steam to remove
benzoic acid. The residue containing the nitrobenzoic acid is
heated to boiling and made slightly alkaline with baryta. Two
litres of water are added and the liquid raised to the boiling
point by passing in steam and then filtered. On cooling, the
barium salt crystallises and is filtered off and decomposed with
hot dilute hydrochloric acid. The precipitated acid is re-
crystallised from water ; m. p. 141°. Yield, 28 grams,